The advantages of adding additives to fuel, especially improvement or intensification of the combustion of the fuel, have been known to the individual skilled in the art for a long time. This applies both to firing systems operated with liquid fuels and to internal combustion engines, for example in motor vehicles.
One very effective and toxicologically harmless solid additive is ferrocene (see German patent DE 25 02 307). Further advantages of fuels containing ferrocene, especially reduction of fuel consumption and exhaust pollution as well as removal or reduction of deposits containing carbon, have also been described in GB 1,477,806, U.S. Pat. No. 4,389,220, DE 3 801 947, and DE 3 715 473.
In both of the latter two publications it is proposed either to add the additive (ferrocene) to the fuel directly in the corresponding concentration of the amounts recommended therein, with mixing, or to prepare a concentrate of dissolved ferrocene and then to add the required volume to the fuel to achieve the desired ferrocene concentration.
EP 0 334 248 proposes addition of ferrocene as an additive to engine lubricating oil for Diesel engines as an advantageous alternative to adding an additive to the Diesel fuel or to an additional dispensing device.